The control of bleeding is essential and critical in surgical procedures to improve the outcomes and to shorten the duration of the surgery in the operating room. Several hemostatic materials including oxidized cellulosic based material has been used as a dressing in a variety of surgical procedures, including neurosurgery, abdominal surgery, cardiovascular surgery, thoracic surgery, head and neck surgery, pelvic surgery and skin and subcutaneous tissue procedure.
It is generally accepted to use multilayered fabrics in connection with medical procedures. For example, multilayered fabrics are used as all purpose pads, wound dressings, surgical meshes, including hernia repair meshes, adhesion prevention meshes and tissue reinforcement meshes, defect closure devices, and hemostats.
U.S. Pat. No. 5,593,441 to Lichtenstein et al describes a composite prosthesis preferably having a sheet of polypropylene mesh that allows tissue in-growth, such as Marlex® mesh. This reference discloses that other surgical materials that are suitable for tissue reinforcement and defect closure may be utilized, including absorbable meshes such as a polyglactin 910 (Vicryl®) mesh. The composite prosthesis of Lichtenstein et al also has an adhesion barrier, preferably a sheet of silicone elastomer.
U.S. Pat. No. 5,686,090 to Schilder et al describes the use of a fleece in combination with a nonabsorbable or absorbable film to prevent mis-growths to adjacent tissue and to reduce adhesions. Schilder et al generally discloses that polypropylene, polyester, polyglactin, polydioxanone or poliglecaprone 25 may be used as the fleece material or the film material.
Published U.S. Patent Application 2006/00084930, to Dhanaraj et al, describes a reinforced absorbable multilayered fabric that can be used in medical devices specifically for tissue engineering applications. The matrix comprises first preparing a repair site for implantation, and then disposing the reinforced absorbable multilayered fabric at site. The first absorbable nonwoven fabric comprises fibers comprising aliphatic polyester polymers, copolymers or blends thereof; while the second absorbable woven or knitted fabric comprises oxidized regenerated cellulose fibers.
U.S. Pat. No. 4,626,253 to Broadnax et al, describes a device that relates to a surgical hemostat for control of bleeding, and more particularly, to a knitted fabric of oxidized cellulose having superior handling and hemostatic properties.
U.S. Pat. No. 7,666,803 to Shetty et al, describes the method of making or reinforced absorbable multilayered fabric that can be used as a hemostat. The matrix comprises first preparing a repair site for implantation, and then disposing the reinforced absorbable multilayered fabric at site. The first absorbable nonwoven fabric comprises fibers comprising aliphatic polyester polymers, copolymers or blends thereof; while the second absorbable woven or knitted fabric comprises oxidized regenerated cellulose fibers. The method also describes the appropriate densities and thickness that can be used to make the matrix in that particular invention.
None of the above references describes or suggests a reinforced absorbable multi-layer of nonwoven fabric with each layer having different densities. Furthermore, none of the above references describes or suggests this nonwoven dual-layered fabric having hemostasis function.